Year	1=low to 6=high
2005	3.2
2006	3
2007	3
2008	3
2009	2.8
2010	2.8
2011	2.7
2012	2.7
2013	2.7
2014	2.7
2015	2.6
2016	2.4
2017	2.4
2018	2.6
2019	2.6
2020	2.6
2021	2.6
2022	2.6
2023	2.6